Method of making piston rings and die for same



W. H. GRAY AND J. W. HOWLETT.

METHOD OF MAKING PISTON RINGS AND DIE FOR SAME.

APPLICATION FILED 056.23, 1920.

1,415,439, PatentedMay 9, 1922.

1 \m v 1 &\ LT \1f WILLIAM HENRY GRAY Ann JOHN wrnmaivr 0mm, or LYr/rmoroN, ENGLAND;

METHOD OF MAKING PISTON RINGS AND DIE. roit SAME.

Application filed December 23, 1920. Serial lq'o. 432,813.

To all whom it may concern Be it known that we, WILLIAM HENRY GRAY, residing at Fern Cottage, Western Road, Lymington, in the county of Hants, England and JOHN WILLIAM Ho-wLErT, residing at The Rosary, Waterford Road, Lymington, in the county of Hants, England, subjects of the King of Great Britain. and Ireland, have invented certain new and useful Improvements in Methods of Making Piston Rings and Die for Same, of which the following is a specification.

This invention has for its object to provide an improved method of making piston rings and the like, and also to provide improved means for use in the manufacture of such rings.

Referring to the accompanying sheet of explanatory drawings which illustrate the manufacture of a piston ring in accordance with this invention Figures 1 and 2 are side elevation and cross section of the initial ring after division.

Figures 8 and 4 are side elevation and cross section of the die in which the said ring is held during hammering.

Figures 5 and 6 are side elevation and cross ection of the finished ring.

In the production of piston rings as shown, a cast iron or other cylindrical shell 7 is machined to produce accurately concentric circular peripheries, and the shell is subsequently parted off to form rings of the required width. Each ring is subsequently divided obliquely or otherwise, or a small piece is broken out of it in the usual manner. A ring at this stage is shown by a at Figures 1 and 2. The adjacent ends of the ring are pulled apart to an extent rather greater than that shown in Figures 5 and 6 and a die is made having a recess whose periphery corresponds exactly to that of the ring in the said stretched or distorted condition. Such a die is shown by b in Figures 3 and 4, the shape of the periphery of the recess 0- in which the ring is placed being approxi-' mately represented by the non-circular line (if. The exact shape of the die may be determined mathematically, but it may conveniently be determined by copying accurately the shape of the ring when distorted as above described. When placed in the die the ring is held in close contact with the periphery of the die recess by a block inner and outer peripheries attached to thedie, the ring being caused to abut against opposite sides of this block. While in the die the ring is lightly hammered around, its inner periphery until it receives a permanent set, the amount of hammering or stressing being varied to suit the outward pressure Specification of Letters Patent. Patfinted lVIay-Q, I

the separated ends of which the ring is required to exert when in service. After this treatment'the finished ring is taken out of the die, and it thensprings inwards to some extent but does not resume its original truly'circular form. A finished ring is shown at Figures 5 and 6.

When in service on a piston, the ,ring'is sprung inwards to allow of its being slipped into the cylinderin which it is required to work,'and it then has its original circular form, but now it tends to expand and in so doing it exerts a' uniform outward radial pressure against the cylinder wall, 1

It is evident that this invention is equally applicable to rings in which the inner pe-v riphery is eccentric to the only difference in the manufacture being that the original ring is machined to the desired eccentric form. i In some cases the ring may be originally shaped to what has above been described as the distorted or non-circular form, in accordance with known practice. Such a ring has a portion removed from it to permit of its being subsequently contracted to the circular form. After having been thus divided, and while possessing it original noncircular configuration, it isplaced in a correspondingly shaped die and hammered as above described. When contracted, to the circular form the ring then exerts a more the outer periphery,

uniform outward radial pressure than when, i

1. In the manufacture of piston and like rings, the holding of a divided ring which" is stretched, or initially shaped, toa noncircular form, in a correspondingly shaped die, and hammering the ring while .thus

held, substantially as described.

2. In the manufacture of piston and likerings, the formation of a ring initially with of circular form, and, after dividing or breaking the ring and distorting the same by expansion, holding the ends of the ring and secure the ring in close Contact with the die substantially us 10 described.

In testimony whereof we have signed our names to this specification.

WILLIAM HENRY GRAY. JOHN WILLIAM HOWLETT. 

